The heart of a computer is a magnetic hard disk drive (HDD) which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The volume of information processing in the information age is increasing rapidly. In particular, HDDs have been desired to store more information in its limited area and volume. A technical approach to meet this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording density, further miniaturization of recording bits is effective, which in turn typically requires the design of smaller and smaller components. This reduction in component size is aided by the ability to maintain the reading and writing elements in a magnetic head in a position closer to the magnetic recording layer of the magnetic medium. This distance between the reading and writing elements and the magnetic recording layer is referred to as the magnetic spacing.
Narrowing the magnetic spacing is a very effective method for improving the recording density of a magnetic recording device, such as a HDD. Reducing the clearance, which is defined as the gap between the lowest point (farthest protruding portion at the ABS) of the magnetic head and the uppermost surface of the magnetic medium has been attempted to reduce the magnetic spacing. A technique used in magnetic recording devices to reduce this clearance relies on thermal expansion of one or more portions of the magnetic head. This thermal expansion is caused by a heater which is positioned near one or more elements of the magnetic head such that applying current to this heater controls the expansion of the one or more portions of the magnetic head to provide a smaller head-to-medium clearance.
However, a smaller clearance may also lead to undesirable interactions between the slider and a lubricant layer of the magnetic medium. Such slider-lubricant interactions may create moguls, ripples, depletions, etc. in the lubricant. Slider-lubricant interactions may also cause the lubricant to accumulate on the leading edge of the slider, thereby negatively affecting the performance of the read and write heads. Moreover, the lubricant accumulated on the leading edge of the slider may fall back onto the magnetic medium's surface, resulting in a lubricant layer having non-uniform thickness. Unfortunately, a non-uniform lubricant layer (e.g. a lubricant layer including moguls, ripples, thicker regions, etc.) may lead to errors during read and/or write operation, as well as allow scratching of the magnetic medium's surface in regions with little to no lubricant.